1. Field of the Invention
Exemplary embodiments of the present invention relate to a light emitting diode package and a method of fabricating the same, and more particularly, to a wafer level light emitting diode package and a method of fabricating the same.
2. Discussion of the Background
In general, a light emitting diode (LED) refers to a light-emitting semiconductor device, and the color of generated light may vary depending on changes in the compound semiconductor materials, such as GaAs, AlGaAs, GaN, and InGaInP.
By applying a current to the LED, electron-hole recombination occurs at the junction between a p-type semiconductor and an n-type semiconductor, which leads to the generation of light in the LED.
Measured characteristics of an LED device may include color, luminance, luminance intensity, thermal and electrical reliability, and the like. Although the device characteristics may be determined by compound semiconductor materials, which are used in the LED device, the structure of a package in which a light-emitting chip is mounted may influence the device characteristics.
A package structure may not realize sufficient heat dissipation characteristics (referring to heat dissipation to the outside of the package structure) when the device generates light, relying only on the development of package components.
Since the LED package may be required to exhibit not only thermal and electrical reliability but also optical characteristics, it may have a structure different from that of a typical semiconductor package.
A lead frame type mold package is an example of an LED package. The lead frame type mold package includes a package body, which is an injection molded resin material that forms a cavity in which a light-emitting chip is disposed, and a pair of lead frames, which are integrally shaped inside the package body to be spaced apart from each other at a predetermined interval. Here, the light-emitting chip is wire-bonded to the lead frames via metal wires.
A ceramic type mold package is another example of an LED package, in which a ceramic substrate is formed by stacking multiple layers of ceramic sheets over one another, in which a light-emitting chip mounted on the upper surface of the ceramic substrate is electrically connected to an electrode pattern formed on the upper surface of the ceramic substrate via metal wires, and in which a transparent resin material encapsulates the upper surface of the ceramic substrate, thereby forming an encapsulant.
However, these mold packages of the related art are limited in the extent to which they can simplify manufacturing processes, enable miniaturization by being reduced in size, and help realize batch processing. Therefore, wafer level packaging technology has been introduced in order to realize the simplification, miniaturization, and batch processing of LEDs.
Korean Patent Application Publication No. 10-2006-0095271, applied for by Park, et al., discloses a method of fabricating an LED package at the wafer level. The wafer level LED package is fabricated by mounting a plurality of light-emitting chips on a wafer substrate, applying a fluorescent paste over the upper surface of the mounted light-emitting chip, curing the fluorescent paste, and cutting the resultant structure at a chip size.
In this method of fabricating an LED package, however, the wafer substrate and the fluorescent paste form heterogeneous bonding and have different thermal expansion coefficients. Therefore, external moisture may penetrate into the package through the interface between the wafer substrate and the fluorescent paste, and thermal deformation may occur, thereby acting as factors that may increase a defect ratio.
In addition, the wafer level LED package of the related art has a limited ability to increase light extraction efficiency by increasing the efficiency of reflection of light to the outside when the light-emitting chip operates, or by increasing the transmissivity of light through a chip substrate of the light-emitting chip.